Generally, a light emitting diode (hereinafter, referred to as an ‘LED’) is a semiconductor device that converts an electrical signal into infrared light, visible light or other forms of light using recombination between electrons and holes, which is one of the properties of a compound semiconductor, to transmit and receive the signal.
Generally, the LED is used in electric home appliances, a remote controller, an electric bulletin board, an indicator, various kinds of automated equipment, optical communication, etc. The LED may be classified as an infrared emitting diode (IRED) or a visible light emitting diode (VLED).
A frequency (or wavelength) of light emitted from the LED is a function to a band gap of a semiconductor material. If a semiconductor material having a narrow band gap is used, photons having low energy and a long wavelength are generated. On the other hand, if a semiconductor material having a wide band gap is used, photons having a short wavelength are generated. Consequently, a semiconductor material for a device is selected based on kinds of light to be emitted.